1. Field
Aspects of embodiments of the present invention relate to organic light-emitting diodes.
2. Description of the Related Art
Organic light-emitting diodes (OLEDs), which are self-emitting diodes, have advantages such as wide viewing angles, excellent contrast (e.g. high contrast), quick response, high brightness, excellent driving voltage characteristics (e.g. low driving voltage), and an ability to provide multicolored images.
A typical OLED has a structure that includes an anode, a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and a cathode, which are sequentially stacked on a substrate. Herein, the HTL, the EML, and the ETL are organic thin films formed of organic compounds.
An operating principle of an exemplary OLED having the above-described structure is as follows:
When a voltage is applied between the anode and the cathode, electron holes injected from the anode move to the EML via the HTL, and electrons injected from the cathode move to the EML via the ETL. The holes and electrons recombine in the EML to generate excitons. When the excitons drop from an excited state to a ground state, light is emitted.